God gave you a brain and I'm sure you know how to use it, so listen up:
You can learn how to write by reading how-to books, trade magazines, taking writing classes, joining a critique group and professional organizations and actually writing.
You can learn how to sell your book by reading how-to books, joining writer's groups, reading The Writer and Writer's Digest, and actually sending your work to editors and agents.
You can learn to market your book by reading how-to books, joining professional writer's organizations, reading The Writer and Writer's Digest and networking with other writers.
Wisdom from the Past:
Carl Jung: Through pride we are ever deceiving ourselves. But deep down below the surface of the average conscience a still, small voice says to us, 'Something is out of tune.'
Carl Rogers: If we value independence, if we are disturbed by the growing conformity of knowledge, of values, of attitudes, which our present system induces, then we may wish to set up conditions of learning which make for uniqueness, for self-direction, and for self-initiated learning.
Carl Sagan: One of the saddest lessons of history is this: If we've been bamboozled long enough, we tend to reject any evidence of the bamboozle. The bamboozle has captured us. Once you give a charlatan power over you, you almost never get it back.
I think we all have a little voice inside us that will guide us. It may be God, I don't know. But I think that if we shut out all the noise and clutter from our lives and listen to that voice, it will tell us the right thing to do.
Use your brain. Listen to your gut. Take the lead. Go write.